Multifunctional radical polymers-enabled rapid charge/discharge and high capacity for flexible self-standing LiFePO4/PETM/SWNT hybrid electrodes

The combination of high output and high energy storage performance at the same time is a long-standing and formidable challenge in electrode technology. Herein, a multifunctional radical polymer binder, poly (ethylenealt -TEMPO maleate) (PETM) is first introduced to construct flexible self -standing organic/inorganic hybrid electrodes, PETM/lithium iron phosphate (LFP)/single-walled carbon nanotubes (SWNT). Notably, PETM plays multifunctional roles in the PETM/LFP/SWNT electrodes as a polymer binder, electrochemical mediator, and auxiliary active material. First, PETM provides strong adhesive strength to generate robust structural integrity, allowing a three-dimensional hierarchical consecutive structure. Second, together with the electrochemical mediation of PETM, the hybrid structure greatly expedites electron/ion transportation, thus bringing fast redox reaction kinetics and high output. Third, PETM offer additional energy storage owing to the electro-activeness of radical groups. Coupled with the self-supporting property of the electrode without any redundant electroinactive components, the electrode energy density can be substantially improved. Profiting from those advantages, the formed electrode achieves exceptional rate performance (97.5 mA h/g at 20 C), extraordinary specific/ areal capacity (173 mA h g-1/8.2 mA h cm -2 at 0.1 C), and ultralong-life cycle under ultrahigh rate (over 2000 cycles at 20 C). More importantly, the electrode can be utilized as a flexible cathode in flexible batteries.